What would theater be — really, what would the entire entertainment-industrial complex be — without people behaving badly?

It’s been a theme onstage since long before Shakespeare got people thieving and cheating in his stories, which makes “Bachelorette” just part of an illustrious tradition of amok-titude (even if the Bard didn’t feature actual strippers in his plays, per se).

But comic mayhem isn’t all there is to “Bachelorette,” says Anthony Methvin, who’s directing the San Diego premiere of Leslye Headland’s edgy 2008 play for Backyard Renaissance Theatre.

“Part of what I love about this piece and Leslye Headland’s writing is the humanity of it,” Methvin says. “Because you’re watching people do absolutely insane things. Things you did at your craziest or lowest, or you can’t imagine doing ever.

“But because of the way she writes these characters, there’s a humanity to them. You’re able to build empathy.”

“Bachelorette” is actually just one part of Headland’s “Seven Deadly Sins” cycle, which so far has yielded six plays. (She hasn’t tackled “Pride” yet.) “Bachelorette” takes on gluttony; everyone in the play is dealing with some kind of addiction or obsession, and illicit substances abound.

The play is the best-known in the “Sins” series, mostly because it was made into a movie in 2012 starring Kirsten Dunst, Isla Fisher and and Lizzy Caplan, with Headland herself directing from her own script.

These days, Headland writes mostly for Hollywood. Speaking of which: Her 2008 play “Assistance” has taken on a new sense of timeliness because it was written in the wake of her four-year stint as an assistant to the now-disgraced film producer Harvey Weinstein.

Methvin has been a fan of the playwright since seeing a production of that play in New York, shortly before he moved here in 2012 with his now-husband, the San Diego actor Tom Zohar. He orchestrated an initial reading of “Bachelorette” at Backyard Renaissance, and the audience response convinced the company to do a full production.

Lauren King Thompson, a wide-ranging local actor who recently joined the administrative staff at San Diego Rep, plays Gena, a kind of accidental bridesmaid with a serious weakness for drugs.

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Appetites more or less define everyone in the play, Thompson says: “You meet these women, and you just see them consuming and consuming and consuming.”

But eventually, “you start seeing the reasons behind the consuming they’re doing — it becomes this really intimate look at their hurt and betrayal.”

There’s also an element, she adds, of how these 30-something characters’ troubles extend to an “addictive, enabling relationship with each other,” reinforcing their mutual identities as “people who are kind of failing at adulting.”

But there’s a silver lining in there somewhere, if you can see it through all the sweet-smelling smoke.

As Methvin puts it: “Yes, they can be horrible people. They also can be amazing friends.”